Lighting devices having light emitting diodes (“LEDs”) have typically required creating the LEDs on a semiconductor wafer using integrated circuit process steps. The wafer is then divided, individual LEDs are placed in a reflective casing, and bonding wires are individually attached to each LED. This is a time consuming, labor intensive and expensive process, resulting in LED-based lighting devices which are generally too expensive for many consumer applications.
Similarly, energy generating devices such as photovoltaic panels have also typically required creating the photovoltaic diodes on a semiconductor wafer or other substrates using integrated circuit process steps. The resulting wafers or other substrates are then packaged and assembled to create the photovoltaic panels. This is also a time consuming, labor intensive and expensive process, resulting in photovoltaic devices which are also too expensive for widespread use without being subsidized or without other governmental incentives.
Other methods of manufacturing photovoltaic devices are also being developed. For example, Hammerbacher et al. U.S. Patent Publication No. 2008/0289688, published Nov. 27, 2008, entitled “Photovoltaic Apparatus Including Spherical Semiconducting Particles”, and Hamakawa et al. U.S. Pat. No. 6,706,959, issued Mar. 16, 2004 and entitled “Photovoltaic Apparatus and Mass Producing Apparatus for Mass Producing Spherical Semiconducting Particles” disclose a method which initially uses spherical diodes having a pn junction formed about the entire sphere, but then introduce manufacturing problems by requiring corresponding micromachining of each individual diode to remove a substantial section of the sphere and its pn junction, to form a recess into an inner, core portion. What was initially a spherical diode is micromachined to become significantly or appreciably aspherical, to create a substantially flat, recessed side having an exposed inner, core portion, in order to access either an n-type (or equivalently, N-type) or p-type (or equivalently, P-type) interior substrate portion of the diode for bonding to an electrode. Once micromachined, the individual aspherical diodes must be properly oriented, individually placed, and bonded to conductors at both the exterior and the recessed interior parts of the diode to produce a resulting device. Again, this is also a time consuming, labor intensive and expensive process, with corresponding difficulties for generating widespread use.
Another method of manufacturing photovoltaic devices, disclosed in Ebert U.S. Pat. No. 4,638,110, issued Jan. 20, 1987, entitled “Methods and Apparatus Relating to Photovoltaic Semiconductor Devices”, utilizes a clear, solid sheet having an array of curvatures on a first side of the clear solid sheet, to form an integrally formed array of abutting solar concentrating lenses with a single index of refraction. The lens panel further has a flat, second side coupled and fixed to a prefabricated panel, with the prefabricated panel having solid conducting layers separated by an insulating layer. In this method, a laser is stepped along each individual lens of the sheet, which focuses the laser beam to micromachine and bore a corresponding hole into the prefabricated panel through the solid, preformed conductive and insulating layers. The resulting array has a large number of very small bore holes which are then filled with either a semiconductor material or prefabricated diodes to create a photovoltaic cell, with each concentrating lens designed to be fifty to 100 times larger than the resulting photovoltaic cell. Due to the focusing of the lens array, separate solar tracking assemblies are required, to move the entire device to track solar positions, because light is focused on the solar cells from only a small range of angles, with light incident from other angles being focused on other, non-solar cell portions of the prefabricated panel. This micromachining method did not gain wide acceptance, possibly due to many difficulties which were not addressed, such as problems of orienting, aligning and placing prefabricated diodes into each bore hole; difficulty creating a semiconductor in the bore holes having a crystalline structure of sufficient quality for efficient functioning; difficulty forming a pn junction in the region of the bore hole covered by the lens panel (for exposure to the focused light); fabrication problems due to the small sizes of the bore holes; difficulty with consistent filling of the bore holes; difficulty bonding the applied semiconductor materials or prefabricated diodes to create fully functioning and reliable ohmic contacts with the remaining (non-ablated), solid conductive layers preformed in the panel; the creation of short circuits between conductive layers from the laser machining debris, etc., for example and without limitation. In addition, this method and resulting apparatus is not useable for creating addressable or dynamic LED displays.
With regard to light emitting devices, various other light emitting apparatus and methods have been oriented toward increasing the amount of light actually emitted from the light emitting device. For example, Lu U.S. Patent Application Publication 2007/0108459, published May 17, 2007, entitled “Methods of Manufacturing Light Emitting Devices”, discloses various lens and light extraction structures and geometries have been developed in attempting to minimize internal reflection, such that light emitted from LEDs is actually output from the device.
Due to such complexities, among other reasons, material and manufacturing costs for photovoltaic devices and LED-based devices has remained too high for widespread adoption. As a consequence, a need remains for light emitting and/or photovoltaic apparatuses which are designed to be less expensive, in terms of incorporated components and in terms of ease of manufacture. A need also remains for methods to manufacture such light emitting or photovoltaic devices using less expensive and more robust processes, to thereby produce LED-based lighting devices and photovoltaic panels which therefore may be available for widespread use and adoption by consumers and businesses.